For many people, the three leading international systems for certifying sustainable buildings – DGNB, LEED and BREEAM – are sometimes used in the same breath and the public perception is that they’re largely interchangeable. But if you take a closer look at the obvious overlaps between the systems, there are actually a number of fundamental differences, so it’s not quite right to consider them synonymous.
1) Sustainable vs green
The first difference between the different systems and their underlying approaches is reflected in the name. The international concept of a ‘green building’ is applied differently by the DGNB by calling it a ‘sustainable building’. This is because the DGNB feels the word ‘green’ does not go far enough. It has close associations with energy efficiency and the ecology, which should be just one aspect of a sustainable approach to building. As a result, the DGNB System is based on an understanding of sustainability that pulls together three factors: ecological, economic and social. Not even considering economic aspects – or only making them subordinate, as is the case with LEED, which is more about focusing on energy issues – goes against the grain of this understanding. The DGNB believes that a building should always be planned and constructed such that
- it is environmentally sound and conserves resources during construction and in use
- it makes economic sense, saves money in the long term and does as much as possible to minimise investment risk
- the main emphasis lies in people, by promoting health and comfort, plus the quality of indoor and outdoor spaces, and that this makes it more probable that a building will be used for longer
- as much as possible is undertaken to consider factors relating to the climate and culture, and that a building is adapted accordingly so that it reflects local needs and the architecture of a culture.
There are three further factors looked at by the DGNB System, and these are also an essential component of sustainability when it comes to planning, constructing and operating a building: technical quality, process quality and site quality. To obtain certification on the very highest level with the DGNB, a building must achieve excellent scores in all topics. This allows the DGNB to ensure that a certified building always reflects the most holistic and sustainable approach possible.
2) Life cycle costing and life cycle assessment
One fundamental concept underlying the DGNB System is that a building should reflect a strict regard for its overall life cycle and consideration should be given to the entire value chain during construction. This begins with the extraction of raw materials and ends with the dismantling of a building and the recycling of components. For the majority of schemes the DGNB uses a reference building life of 50 years. This approach to considering the life cycle of a building transcends the entire DGNB System and all sustainability factors. In terms of environmental quality, a building is required to have a good score for the life cycle assessment (LCA). This involves ascertaining the overall use of resources and impacts on the environment, for instance emissions that cause environmental damage. This factor is assessed for the entire life cycle. It therefore takes into consideration whether higher outlays during construction can be amortised because a building performs better (in environmental terms) during use.
Specifically assessing building materials and harmful substances in a building involves looking at the entire value chain – from the impact of actual manufacture to installation, use and operation, and material disposal after use. When it comes to economic factors, the DGNB certification covers the cost of energy and water, construction costs and follow-on costs – for example for any cleaning, maintenance or renovations that may be required in the future but can already be estimated today. The method used for this assessment is Life Cycle Costing (LCC). The process quality highlights the importance of consistently applying life cycle principles over time. This involves laying down requirements for each relevant factor from demand planning to disposal.
Consistently focusing on the overall life cycle of a building and how the outlined methods are applied is considered an intrinsic part of the DGNB System from the very beginning. Other certification systems in the market continue to underemphasise certain factors in this regard. By consistently applying its life cycle methods, the DGNB has successfully encouraged a number of manufacturers to take action, for example by systematically issuing information on the environmental impact of their products with documentation like the Environmental Product Declaration (EPD). Building owners find the results of a DGNB assessment useful for long-term decision-making and introducing effective measures; project managers and investors use the life cycle sustainability figures when they talk to potential customers.
3) Overall performance vs the evaluation of individual measures
Whether it makes sense to construct a building this way or that way depends on a whole variety of different factors, and these are often influenced by the context within which the building is needed or constructed. In this respect, the DGNB System works very differently to other certification systems because it is not a rating tool that looks at measures taken individually. Instead, the DGNB System lays emphasis on trying to enhance the overall performance of a building. To this end, results are assessed according to the actual impact on a building and not just whether a checklist can be ticked off because measures have been implemented. The focus throughout – for all criteria – lies in the overall goal that needs to be achieved. As a result, it is the responsibility of investors and architects to find an appropriate solution or identify the best course of action, and this provides enough leeway for people to come up with new and innovative ideas. Assessment of the life cycle costs of a building leaves room for additional investments in innovation, which makes the evaluation fair by acknowledging people’s willingness to try something different.
The different approaches are also reflected in the life cycle assessment. With the LEED system, simply carrying out a life cycle assessment is rewarded, whereas the DGNB takes a more integrated approach, seeing it as a means for determining the scores that will be used for certification based on certain benchmarks. A similar approach is taken with EPDs. LEED gives a reward just for pulling together EPDs, irrespective of which products they relate to and how they are applied to a building. With the DGNB System, EPDs are used to ascertain fundamentals in order to collect the right information for a life cycle assessment – so that it provides the closest possible reflection of reality.
There are also differences in how evaluations are used for each criterion. With LEED and BREEAM, evaluations are based on whether something ‘is or is not fulfilled’, whereas the DGNB System uses more differentiation with levels based on targets, reference values and limits. As a result, the DGNB System ensures that individual factors that drive sustainability are not overlooked. It also acknowledges whether a project works through the criteria in a meaningful way and does not just try to maximise scores.
4) Adaption of requirements vs one fits all
To date, the DGNB System has been used to certify buildings in more than 20 countries worldwide. Importantly, especially compared to LEED, the DGNB adapts the criteria referred to in requirements according to regional conditions and circumstances. For example, these may be regulatory requirements, the specific nature of a market or the regional climate. For the latest Version 2018 of the DGNB System for new buildings, the DGNB is currently drafting differentiated guidelines for using the system in international markets. In concrete terms, this involves adjusting certain reference values and limits laid down within individual criteria so that there are starting points or comparative values that match the regional context. Nonetheless, if achieving targets could result in a maximum score for individual indicators, these targets are kept the same on an international level, even if there may be different ways to hit these targets. As a result, all buildings that are certified under the DGNB System depend on higher target values. Not only does this make it possible to draw comparisons beyond the individual borders of countries, it also makes a positive contribution to the environment we build around ourselves on a more holistic level.
In the second part of the series you will learn more about the logic behind the awards, the different DGNB schemes and the organisations behind the different systems.